PSP Game Crashes After Adding or Subtracting Even One Character in a File

Hello all,

I'm trying my hand at a bit of homemade re-localization. Basically, I'm taking a game with a ton of typos and grammar mistakes and fixing them (that's the plan anyway). Maybe I'll look into replacing the corny English sound clips with the originals as well, but one step at a time.

For now, ALL I want to do is alter text. Starting as small as possible, I:

• Found the first line in the game.
• Ripped the game from UMD, then used UMDGEN to extract the game files and locate the file that contains that first line.
• Altered that first line in the file by ADDING just a single character, saved the file, and re-ISO'd the data in UMDGEN.

Now, I can launch the game, and make it through the opening cinemas, but it always crashes just before the first scene of actual gameplay, in which the altered first line appears.

However, if I CHANGE one character -- say an "n" to a "p" -- rather than adding a character, everything is fine. The game plays normally and the changed character displays like it should. Likewise, everything is fine if I remove a character from one line, but add one to another.

So, it seems the filesize being different is what's causing the crash. Obviously, I could work within this limitation, but it's not ideal if I want to really have my way with the script. So, finally my questions:

• Like I said, I'm very new to all this. Is it a known thing for PSP game-hacking that there's a table somewhere in the code that references expected filesizes for each file, and if they ever don't match, the game will crash? I tried searching through all the game files for the full path of the one I'm changing, as well as its exact size before being altered (119,088 bytes), but didn't turn up anything.
  
• Regardless, is there any way around this limitation where I'll be able to increase or decrease filesizes at my discretion?
  

By the way, the file I'm altering is not pure text unfortunately. There's a bunch of crazy characters as well when viewing in Notepad or Vim that I can only assume is compiled code. The file type is "po1" which seems to be a custom file type for this game as I couldn't find any info on the web.

Thanks in advance. Also, please let me know if there's a better place to ask this sort of question.

My Info:

PSP-1000
Firmware: 5.00 M33-6
No customization -- only thing installed is a GBA emulator and Mother 3

Here's a picture of Kipi for reading this far:

<3 Kipi

Ehm...

Did you add a byte to the file, as in insert a character with a hex editor? Or did you add a byte to the string by overwriting something after it? If you just insert a character and thus make the file bigger, the game is garantued to crash because all the pointers (the address book of strings) point to the wrong directions then. If that's the problem, look up the documents about pointer hacking.

The problem with hacking and cd-based media is that if you change the file size of a file to be over the amount it is accustomed to when the game is built, it tends to break the game.

You can usually decrease the size, usually, but never increase it.

This sounds like it is the case with whatever game you're working on.

~DS

You can usually decrease the size, usually, but never increase it.

You *can* increase the size, provided that you do know what you're doing. As long as you don't break ram boundaries or overlay bss segments, expansion is possible and works just fine.